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            <h2 class="title" style="clear: both"><a id="opendbenvironment"></a>
		Opening and Closing the Database Environment
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      <p>
    This section of the tutorial describes how to open and close the
	database environment. The database environment manages resources
	(for example, memory, locks and transactions) for any number of
	databases. A single environment instance is normally used for all
	databases.
</p>
      <p>
    The <code class="classname">SampleDatabase</code> class is used to open and close the
	environment. It will also be used in following sections to open and
	close the class catalog and other databases. Its constructor is
	used to open the environment and its <code class="classname">close()</code> method is used
	to close the environment. The skeleton for the
	<code class="classname">SampleDatabase</code> class follows.
</p>
      <a id="cb_java_sampledatabase"></a>
      <pre class="programlisting"><strong class="userinput"><code>import com.sleepycat.db.DatabaseException;
import com.sleepycat.db.Environment;
import com.sleepycat.db.EnvironmentConfig;
import java.io.File;
import java.io.FileNotFoundException;

public class SampleDatabase
{
    private Environment env;

    public SampleDatabase(String homeDirectory)
        throws DatabaseException, FileNotFoundException
    {
    }

    public void close()
        throws DatabaseException
    {
    }
}</code></strong> </pre>
      <p>
    The first thing to notice is that the Environment class is in
	the 
         
        <span>com.sleepycat.db</span> 
    package, not the com.sleepycat.collections
	package. The 
         
        <span>com.sleepycat.db</span> 
    package contains all core Berkeley DB
	functionality. The com.sleepycat.collections package contains
	extended functionality that is based on the Java Collections API.
	The collections package is layered on top of the 
        
        <span>com.sleepycat.db</span>
	package. Both packages are needed to create a complete application
	based on the DB Java Collections API.
</p>
      <p>
    The following statements create an 
    
    <a class="ulink" href="../../java/com/sleepycat/db/Environment.html" target="_top">Environment</a>
    
	object.
</p>
      <a id="cb_java_sampledatabaseconstructor"></a>
      <pre class="programlisting">public SampleDatabase(String homeDirectory)
        throws DatabaseException, FileNotFoundException
    {
<strong class="userinput"><code>        System.out.println("Opening environment in: " + homeDirectory);

        EnvironmentConfig envConfig = new EnvironmentConfig();
        envConfig.setTransactional(true);
        envConfig.setAllowCreate(true);
        envConfig.setInitializeCache(true);
        envConfig.setInitializeLocking(true);

        env = new Environment(new File(homeDirectory), envConfig);</code></strong>
    } </pre>
      <p>
    The 
    
    <a class="ulink" href="../../java/com/sleepycat/db/EnvironmentConfig.html" target="_top">EnvironmentConfig</a>
    
	class is used to specify environment configuration parameters. The
	first configuration option specified — <code class="methodname">setTransactional()</code> —
	is set to true to create an environment where transactional (and
	non-transactional) databases may be opened. While non-transactional
	environments can also be created, the examples in this tutorial use
	a transactional environment.
</p>
      <p>
    <code class="methodname">setAllowCreate()</code> is set to true to specify
	that the environment's files will be created if they don't already
	exist. If this parameter is not specified, an exception will be
	thrown if the environment does not already exist. A similar
	parameter will be used later to cause databases to be created if
	they don't exist.
</p>
      <p>
    When an <code class="classname">Environment</code> object is constructed, a home
	directory and the environment configuration object are specified.
	The home directory is the location of the environment's log files
	that store all database information.
</p>
      <p>
    The following statement closes the environment. The environment
	must be closed when database work is completed to free
	allocated resources and to avoid having to run recovery later.
	It is recommended that databases are closed before closing the
	environment.
</p>
      <a id="cb_close"></a>
      <pre class="programlisting">    public void close()
        throws DatabaseException
    {
<strong class="userinput"><code>        env.close();</code></strong>
    } </pre>
      <p>
    The following getter method returns the environment for use by
	other classes in the example program. The environment is used for
	opening databases and running transactions.
</p>
      <a id="cb_getenvironment"></a>
      <pre class="programlisting">public class SampleDatabase
{
    ...
<strong class="userinput"><code>    public final Environment getEnvironment()
    {
        return env;
    }</code></strong>
    ...
} </pre>
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